STUDY OF THE CA AND SR + HN3 REACTIONS - INDIRECT EVIDENCE FOR THE FORMATION OF THE METAL IMIDES

The reaction of Ca and Sr atoms with HN3 has been studied in a beam-gas configuration. Emission from electronically excited metal atoms (1P and 3P) and the metal hydrides (A2II and B(2)SIGMA+) was observed. Additional molecular chemiluminescence was also seen and assigned to production of electronically excited MOH. By the deliberate addition of oxygen-containing molecules, the formation of MOH* was confirmed as being due to a secondary reaction involving O2 impurity in the HN3 samples. In laser fluorescence experiments, ground-state MOH and MN3 were detected. An unsuccessful search for CaNH laser fluorescence excitation was also conducted. All of the observed emissions can be explained as arising from secondary reactions of the metal imide (MNH) formed in the M + HN3 primary reaction. A kinetic model is presented to explain these observations, and it is concluded that the M + HN3 reaction proceeds mainly by formation of MNH, rather than MN3. Bounds on the M-NH bond dissociation energy are also derived.